Squirrel-cage motor



D, L. L lNDQUlsT ET AL SQUIRREL CAGE MOTOR Filed May 18. 1923 5724701? PQM /2 POL E5 2 pOLES y /2 /CO/.E

paths through the sections 6, between the top of the slots el; and the outer periphery of the ring. By properly locating the slots l relatively to the outer periphery ol the ring the sections (5 can he made to give the regive the required resistance vtor that speed.-

To obtain substantially the same resistance in all positions of the rotor, the slots Il in alternate rings are staggered as shown in Figure 6.

The ring illustrated in Figure 3 is more particularly designed in respect to the are shaped slots for a three-Speed motor. Two rows of slots are shown, slots 4f in the outer row and slots 7 in the inner row. The slots 4 liX the current paths for the slow speed, the slots 7 the paths for the intermediate speed and the entire ring the paths for high speed. In the low Speed the current paths are confined to the sections 6 in the ring; in the intermediate speed to the sections 6 and 8; and in the high speed to 'the sections 6, 8 and 9. The location and Width of the slots 7 Will determine the. Width of the Sections 8. The length of the slots 7 is the same the intermediate pole pitch, and the number of slots 7 is one half of the number ot the poles of the intermediate speed.

Figure 3 also illustrates an end ring provided with radial slots 3 similar to Figure l as Well as are shaped slots 4- and 7. The rin dial slots afford means for proportioning the bar to bar resistance, as has been stated above, and the are shaped slots afford means for proportioning the resistance of the end ring itself as best suited to give the required rotor resistance for the different speeds.

The principle of the invention as applied to the arrangement of the slots as illustrated in the rings in Figures 2 and 3 can he used for practically any ratio of speeds. For examples, the end ring illustrated in Figure 2 is designed for' a Q-Speed motor with a lQ-pole slow s eed, the number of poles in the high speed eing immaterial; and the end ring illustrated in F igure 3 is designed more par; ticularly with respect to the are shaped slots for .a 3-speed motor, with a l2-pole slow speed, a Q-pole high speed and a A1f-pole intermediate speed. In the end ring as illustratedin Figure 2 for a -speed motor, it may be found'that the radiating surface is not enough, and if so, the ring illustrated in Figure 3 can be used for two-speeds wherein thenumber of slots in the inner row for high speed is determined by the number ot' poles for' the high speed .in question, as has been already explained, and in which ring the current paths for the high spe d are conn fined to the sections (i and e, and the addiA tional radiating surface retpiired for high .speed is provided for by the sections 9 o' the ring, through which no currents flow for either oi' the two speeds.

This plan ot confining the rotor currents inthe end rings to definite paths for the various speeds ati'ords means for obtaining;` the required rotor resistance for all speeds, as has been stated shore, and quiet operation, and permits usingr Sufficient rmiiating` surface to radiate the heat eenerated in the e rotor. s

The slot fl is coiled are shaped above, but the term arc shape is not designed n or intended to confine the shape of the slot l to the shape of an are, as it is plain that said slot may he straight, 'for example, es shown in Figure 1l. l

ilhat We claim and desire to secure by Letters Patent ot the United States is: f

l. ln a multi-speed induction motor ofthe type wherein the different Speeds are obtained by operating with di'lierent numbers o't stator poles, a squirrel cage type rotor comprising an end ring connected to all the rotor hars and provided with substantially circumferential slots for determining the required rotor resistance :tor each number of poles.

:2. In a multi-speed induction motor of the type wherein the dilierent speeds are obtained bj; operating with different numbers o stator poles, a squirrel eageetype rotor comprising an end ring for th' yeter bars, said end ring being provided with substann tially circumferential closed slots for determining; the requiredrotor resistance :for each number of poles. l

3. in a multi-speed induction motor of the type wherein the different Speeds are obtained by operating` with diierent numbers of stat-or poles, a squirrel cage-.type rotor comprising an end rino; connected 'to all the rotor bars and 4prmfided with a series of sub stantislly circumferential closed slots for de' terinining the required rotor resistance for two oi said pole numbers, said slots being arranged on a circle having its center on the motor axis and et a number equal to one' h alf of one of said two pole numbers. I

Il; In a multi-speed induction motor of the typey wherein the diiiereiit speeds are ohtained by operating with diderent numbers ico llt:

imi

of stator poles, a. squirrel. cage type .rotor iso . 'the fe'rept numbexs stator pda@ maf ammg the reqmrsd rotor mslbvam number '01; poles7 55nd :means comp:

provided Wfh SEMS, aa'ilgd @item3 N- tally.

G. n 'a multi-Swed squ' indu@ 11.3. tion motor of the' yp@ Wmln im df Liam jm@ ont speeds (fu-@obtained by @parmi pds different number of stato/y pees ,manna 15m.' femi m 25 obtaining the required mim' cssamc@ im' the largest nurnwer pmes, Said means mm! plsup; an @mi yimg to :d o di the `o- Lor bars, and j; f1. L@ equally spaced 5101s cir" LJ bren m be-rs; of Ubin) h@ wr the im it man compr im am; ung' i ries @iff c wmf@ @u riss of equally spa n menaly, e 'equa'io the diafsms md the mumbai of Sims am ingest number of 230k?,

motor of dw ein Wbw@ ff'wenz 3,1 v Oblaimi'. A cA ent mmlbem rai si far di taining the requl me: ifm' each number of p comprsmg an and Fmg; mow' Siam aaah series being arranged, @"1 mit enrol@ and @ne number off series being at eas ,said mean @ammisequal to one. less man ilu, number an end DI sots,

speeds am Obtained by operating ferent numbers; of stai-,0r poles? obtaining the required mtm each number of poles, said manfs gmmpr f. poles, Hm enth of Isin@ t v ance I Leid/ee one series being one-haiti "the ierget nunibe o\polee.

tfincd by operutinj'.;` with diiierentnumbers oi' stator poles, a squirrel cage type of rotor provided with means for determining1 the required rotor reeistunce for euch nuinber of poles, Suid :means comprising an end lringcounected'to ull the rotor bars and provided with circumferential slots und radial Siete, the rudui slots bein-g urrunged to extend be.-I trfeen the rotor bare from the outer periphn ery oi the ring.

l?. in u squirrei cage induction metete, ineens for obtaining the requirecrotor resietence, said nieuns comprising en end ring having closed Slots, ghe number ci slots beone-hul the niunoer of stator fgnrieex Suid slots being,` arranged eubetuntiulljgf to connue the rotor curren portions of tbe ring and to cause remainder oi the ring uct ne udditionei rudieting sur face.

i8. in u niulti--speei squirre induction motor of the .jupe wherein the different speeds :are obtained by operating with diiiierent ruuuberri; stator poles, Ineens for obtniniruf the requiredl roter resistance Jfor euch number of peice, Suid means comprising un end rino' havin@ slots. said slots being' :arranged substentmily 'to connue the Troor currents to certain portions o'fi the ring undA to cause the remainder of the ring to act us udditio`V ruf" ing surface i9. in u nn1ltiepeed induction motor oi ihn type wherein the diiii'crent are eb tfgined by operating' with different numbers oi' stator poles, uirrei cage Jpe of rotor 1rrovided Awith i in for detern'iining the required rotor re Mince for Gueb. number` or poles, f' id ineens comprising end rings euch end being connected to :di the rotor here und provided *with slots3 the slots in one ring being' arranged in ered reietion to the slots .munother ring,

lll in u multi-Speed induc )u nioi'or of the type wherein the. dil'erem are obuned by operating; with diii'ercnt numbers oi .etutor riolee, u rotor comprising u t ruriuirc' active conductors und en end une; 'lA iid cfr'iuductoi., l, cud ring; being prof- "l with u ecrics or closed Slots, the nuincert ber of slots being equal to one-half of one of the pole numbers.

:21. in u inuitifspeed induction motor of the type wherein the di'erent speeds are obtained by operating with different numbers etutor poles, u rotor comprising a core currying active conductors andan end ring connected to ull sind conductors, said end ring; being provided with a series of closed Slots arranged on a circle having its center on the niotor axis, said slots extending substintiuliy circuniierentially of said circle and euch of Suid slots being of a length equal to the dists. ce between adjacent slots.

22. in :i multi-speed induction motor of the tyye wherein the diii'erent Speeds are obtained by operating with different numbers of stator poles, e rotor comprising a core carrying active conductors and an end ring connected to ail seid conductors, said end ring being provided with evseries of closed slots arranged on e circle having its center on the motor axis, said slots extending Substentialiy circumferential@ of said circle und being` equally spaced, the length of each of said slots being' equai to the distance between adjacent Slots and the number of Said slots being` equai to onehalt of one of the pole numbers.

23, in an induction motor, u plurality of end rings, euch end ringbeing provided with equally spaced closed slots, the slots in one end ring;I being arranged in staggered relation to the Slots in another end rino'. e

in induction motor, u plurality of nd ringe5 euch end ring;r being providedwith ioeed'elots, the siete in one end ring being irrunged in staggered relation to the slots n another end ring.

A rotor for zin-induction motor com-` prising e core carrying active conductors and end ringe connected to ull seid conductors, euch end ringy being; provided with e series of ez'uully spaced elihetuntiaibY circumferentiul siete of equal length, said slots beingl arrunecd en u circle haring its center on the motor el -u the sloth' iu one end ring being urraunged in stuugrcrcd relation to the slots in another cud ring.

In testimony n'liereoir naines reliure signed our to this specifimiion. Dfii) lNiQ-UST.

JACOB d LEVS. 

